MOSCOW (Reuters) - Russia's communications watchdog Roskomnadzor said on Monday it would check next year if Twitter has complied with the law requiring all companies to store personal data of Russian citizens on Russian soil.

"We can certainly say that we will check them until the end of 2018 to make sure they delivered on their promises," Roskomnadzor head Alexander Zharov told website RT.

Zharov referred to a letter from Twitter management saying the company planned to localize the data of the Russian citizens by mid-2018.

Last year Russia blocked access to social networking website LinkedIn, owned by Microsoft, after a court found the firm guilty of violating Russia's data law.